The truss as a structural member for use in bridges and buildings has been well known for well over one hundred years. All-wood trusses and all-steel trusses have come into wide usage. The use of composite trusses which utilize wood chord members and steel web members first came into commercial usage about 15 years ago. These trusses may be found in the teachings of Troutner U.S. Pat. No. 3,422,591 and Birkemier U.S. Pat. No. 3,570,204. The steel web members are connected to the wood chords at the joints by a simple round pin which penetrates a transverse bore in the wood. Although the pin and the steel web members are obviously capable of attaining very high stresses, designers have been limited in taking advantage of these high stress valves because the wood chord has a tendency to split at the joint. While the low value joint due to wood chord splitting has been an obvious and well identified problem for the past 15 years, the truss industry has not solved the problem. Much activity, in the meantime, has occured in designing special end joint fittings, many of which are covered by patents, but the problem of chord splitting in trusses which have "bolt-through-wood" joints has remained up to the time of the present disclosure.
"Obvious" solutions of encapsulating the wood chords in steel at the joints to prevent wood splitting have proved impractical in terms of material cost, manufacturing costs, and installation costs for medium and heavy trusses.